Bitter orange

The bitter orange or bitter orange (Citrus aurantium L.) is a citrus plant with an orange-like fruit. The bitter orange is a cross between grapefruit (Citrus maxima) and mandarin (Citrus reticulata). The bitter orange grows as an evergreen, up to 10 m high tree with mostly thin and short branches. The leaves are oval and contain oil glands. Citrus aurantium produces white, strongly scented flowers. The fruits are roundish with strong orange-coloured skins, which are slightly thicker than those of the orange.

The outer fruit peel is used to make candied orange peel and the whole fruit is used to make orange marmalade. The outer fruit peel is first peeled off, crushed and later added to the marmalade. The peel and juice of the bitter orange are used to produce the Curaçao liqueur and the Italian bitter orange lemonade Aranciata Amara.

Three different fragrance extracts are obtained from the bitter orange:

• From the blossoms, the essential neroli oil is obtained by steam distillation, also called bitter orange flower oil or orange blossom oil. Its production is complex; from 1000 kg of white flowers 1 kg of essential yellowish oil can be obtained. The essential oil of bitter orange blossom contains mainly terpenes (more than 90%), especially limonene; furthermore linalyl acetate, neryl acetate, geraniol, citronellol, nerol. In small quantities also linalool and terpineol.
• Petit grain oil is obtained from the leaves, small twigs and unripe fruit.
• The bitter orange oil (bitter orange oil) is extracted from the fruit peel by centrifuging or pressing. Bitter orange oil is, for example, a fragrance component in Eau de Cologne.

Neroli oil has a calming, relaxing and mood-lifting effect. Furthermore, it has antiseptic (also antimycotic), antispasmodic and digestive effects.

Extracts of bitter orange oil can cause contact sensitization as well as photoallergic reactions. The DKG has so far tested 2% of bitter orange oil in Vaseline (see below fragrances and essential oils). This test application is no longer available. In this respect, a 5% test solution is now (as of 2016) recommended.

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